The OMM Ultra Flexi Cup is a super light, durable and reusable cup. It's flexible design allows you to crush the the cup and stuff it anywhere, from your running vest to your camp kit.

OMM says:

A flexible cup for use on the move for a quick drink or for use at an overnight camp. The durable thermoplastic allows for small compression and easy storage while the shaped lip allows easy filling and drinking.

OMM's Ultra Flexi Cup 200ml is a really handy little cup. Not only can it be crushed into tiny pockets without getting damaged, it can also be frozen or filled with hot water. It also remains free standing, even when empty. With many race organisers requiring you to take your own cup to reduce the need disposable cups and therefore extra waste at events, this is a great option.

The cup features an integrated finger loop which is for providing support when drinking or pouring. The loop is quite thin so there's a good chance it could snap over time but it would still be a usable cup. Pretty good for the low price and weight.